Piston.



G. E. CHEDRU.

PISTON.

APPLICATION mso MAR. 16, 191s.

1,220,070. A Patented Mar. 20,1917.

GUSTAYE EMILE CHDRU, OF LEVALLOIS-PERRET, FRANCE.

PISTON.

Specification of Letters Patent.

Patented Mar. 20, 1917.

Application filed March 16, 1916. Serial No. 84,662.

To aZZ lwhom iz? may concer/f; Y

Be it known that I, GUSTAVE EMILE CHDRU, a citizen of the French Republic, residing at Levallois-Perret, Seine, France, have invented certain new and useful Improvements in Pistons, of which the following is a specification.

This invention relates to pistons, and more particularly to pistons for charging pumps in two-stroke explosion engines.

The invention has for its object to make admission take place only when the piston has completed part of its suction stroke, and to avoid an excessive depression.

The invention comprises a piston formed in two sections, one of which constitutes the piston proper and is provided on its operative face with an annular groove such that a passage is formed between the piston and the wall of the cylinder, the other section serving as a iiap valve and being constituted by a ring engaging the operative face of the piston proper, so that it extends the said face to the wall of the cylinder.

In the accompanying drawing, by way of example, the single figure shows, in partial vertical axial section, the piston of the charging pump according to this invention.

The invention is illustrated, for example, in connection with a `two-stroke explosion engine with a charging pump of the kind described in an application filed in the names of Charles Maurice Philippe Montbarbon and myself, February 27, 1914, Serial No. 821,469, in which the charging pump is constituted by an annular body a inclosing the cylinder b of the engine along a portion of its length, a piston c independent of the piston (l of the engine, a port e establishing communication between the pump chamber and the engine cylinder, and a port f establishing communication between the source of fresh gas and the inner chamber of the pump, the said port f beinguncovered by the pump piston when ithas accomplished a portion of its suction stroke. This invention obviates the disadvantage offered by such engines, that is to say, the infiltration of combustion gases into the pump body owing to the strong depression produced in the said body by the pump piston when the latter, in effecting its suction stroke, has not yet uncovered the port 7 establishing communication between the pump chamber and the source of fresh gases.

This is effected in the following manner:

An annular piston c is employed in the upper portion of the operative face of which is provided an annular recess 01 sothat the operative face does not come into contact with thecorresponding wall of the cylinder a in which it is mounted.

An annular part g is provided, fitting the cylinder c in which the said piston c is mounted, and of an inside diameter slightly smaller than the diameter of the operative face ofthe piston. The said part is very thin near its central hole, and at its outer circumference, is so thick that it can be provided with one or more rings g1. This part is mounted on the piston with its inner flange resting on the operative face of the piston.

Thus the piston is provided with a sort of flap valve which, as soon as a depression is produced in the pump chamber, will open and establish communication between the latter and the fresh gas inlet, long before the inlet port f for the said fresh gases is uncovered by the piston c; the said valve g adhering, owing to its inertia, to the operative face of the piston when the latter begins its compression stroke, and becoming detached for the same reason, as soon as the said piston begins its suction stroke. This result ,is more noticeabley as the speed of working becomes greater.

The piston c may-also have a spring h calculated so that it normally keeps the part forming the valve, in engagement with the operative face of the piston, the said spring being lpreferably constituted by a ring provided with a certain number'of branches in the form of a star, and maintained on the piston` by means of an annular screw h1 screwed into the piston. Y

The valve g may also have a number of ribs g1@ projecting from its inner wall and adapted to be used as guides for the said valve. A

Obviously the invention is not limited to the construction described, but comprises any modifications within'the scope of the claims.

What I claim as my invention and desire to secure by Letters Patent is:-

1. In a pump for the chargingof twostroke explosion engines, the combination, with a cylinder, of a piston working therein and comprising two sections, one of which forms the piston proper and is provided on its operative face with an annular groove such that a passage is 'formed between the piston and the wall of the cylinder, the other section forming a flap valve and being constituted by a ring engaging the operative face of the piston proper, so that it extends the said tace to the wall of the cylinder.

2. In a charging pump, the combination with a cylinder; of a piston working therein and comprising two sections. one of which forms the piston proper and is provided on its operative tace with an annularl groove such that a passage is formed between the piston and the wall of the cylinder, the other section forming a tlap valve and being constituted by a ring engaging the operative face of theI piston proper, so that it extends the said tace to said cylinder wall, and a spring for maintaining said liap valve in such engagement embodying a ring having a plurality of branches radiating therefrom and bearing against the flap valve.

3. In a charging pump, the combination with a cylinder; of a piston working therein and comprising two sections, one ot' which forms the piston proper and is provided on its operative face with an annular groove such that a passage is formed between the piston and the wall of the cylinder, the other section forming a flap valve and being constituted by an an nlar member engaging the operative face of the piston proper, so that it extends the said tace to said cylinder wall, said annular member having a packing ring at its periphery and also having a plurality of gulde ribs projecting from its inner wall.

4. In a charging pump. the combination with a cylinder; of a piston working therein and comprising two sections, one of which forms the piston proper and is provided on its operative face with an annular groove such that a passage is formed between the piston and the wall of the cylinder, the other section forming a Hap valve and being constituted by an annular member engaging the operative face of the piston proper, so that it extends the said face to said cylinder wall, said annular member having a packing ring at its periphery and also having a plurality of guide ribs projecting from its inner wall, and spring means for maintaining said annular member in such engagement.

5. In a charging pump, the'combination with a cylinder; ot' a piston working there- \in and comprising Vtwo sections, one ot which forms the piston proper and is provided on its operative face with an annular groove such that a passage is ormed between the piston and the wall of the cylinder, the other section Aforming a 'liap valve and being constituted by an annular member engaging the operative Jface of the piston proper, so that it extends the said 'tace to said cylinder wall, said annular member having a packing ring at its periphery and also having a plurality of guide ribs projecting from its inner wall, and a spring lor maintaining said flap valve in such engagement embodying a ring having a plurality of branches radiating therefrom and bearing against the flap valve.

6. In a charging pump, the combination with a cylinder; of a piston working therein and comprising two sections7 one ot which forms the piston proper and is provided on its operative face with an annular groove such that a passageis formed between the piston and the wall of the cylinder, the other section forming a {iap valve and being constituted by a ring engaging the operative tace of the piston properso that it extends the said face to said cylinder wall, and spring means for maintaining said flap valveJ in such engagement.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

GUSTI-IVE EMILE CI-IICDIIIT. iVitnesses Crus. I). PnnssLY, PAUL BLUM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents., Washington, D. C. 

